A conducting wire `xy` of lentgh `l` and mass `m` is sliding without friction on vertical conduction rails `ab` and `cd` as shown in figure. A uniform magnetic field `B` exists perpendicular to the plane of the rails, `x` moves with a constant velocity of

Options

A. `(mgR)/(Bl)`
B. `(mgR)/(Bl^2)`
C. `(mgR)/(B^2l^2)`
D. `(mgR)/(B^2l)`

Answer

C

Explanation

Bil =mg or `B(Bvl)/Rl-mg or v-(mgR)/(B^2l^2)`